ProtistsBiology 2

Unit 2

General Info of ProtistsVary Considerably Eukaryotes Some single celled, some multicelled Some with cell wall, some without cell wall,

some with “shells”(sectretions or processed sand just beneath plasma membrane

Some with cillia, some with flagella, some with pseudopods

Some heterotrophic, some photoautotrophs Most asexual and sexual, some only

asexual

dinoflagellate

euglenoid

diatom

Red algae

Slime mold

Found in freshwater, marine, and moist terrestrial habitats.

1st seen by Leeuwenhoek in 1675 Some species of protozoan are parasitic Many serve as food for other organisms in

aquatic habitats, called zooplankton

Protists are very diverse, and probably represent several different evolutionary lineages, more distinct from each other than plants, animals, and fungi are.

Protozoan Evolution

Protists are thought to be the 1st eukaryotes, evolving 1.5 billion years ago

Thought to have evolved by endosymbiosis› Process where a prokaryote lives inside

another becoming dependent upon each other

Protists can be divided into plant-like, fungus-like, and animal-like forms.

Animal like protists…AKA protozoans

Classified by the way they move› Cilia, flagella, pseudopodia…

Zoomastigina

Common name is zooflagellates Move via flagella lacks photosynthesis and other plant-

like characteristics Heterotrophic organisms Some may be parasitic

Examples of Zoomastigina

TrypanosomaLeishmaniaGiardiaTrichonympha

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23

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Sarcodina Commonly called sarcodines Pseudopods Heterotrophic Includes

› Amoeba › Radiolaria› Naegleria

Found in freshwater, marine, and moist soil habitats

Usually reproduce asexually Cytoplasm consists of clear, out

ectoplasm and granular, inner endoplasm

Amoeba move by extending cytoplasm (cytoplasmic streaming) then pulling the rest of the cell along behind.

Pseudopods form when the inner cytoplasm or endoplasm pushes the outer cytoplasm or ectoplasm forward to make a blunt, arm-like extension

Also use pseudopods for feeding by surrounding and engulfing food particles and other protists› phagocytosis

Or food is surrounded by a pseudopod and then this part of the cell membrane pinches together forming a food vacuole› endocytosis

Cytoplasmic enzymes digest the food and undigested waste leaves by exocytosis

Most sarcodines use contractile vacuoles to pump out excess water

Oxygen and CO2 can diffuse through the cell membrane

May form hard, protective inactive cysts, when conditions become unfavorable (drought, heat, lack of nutrients….)

Can react to certain stimuli such as light

Amoebas in Action

Some contain hard shells made of calcium carbonate

Foraminifera – CaCO3 with holes for pseudopodCan build up in ocean and form lime or chalk

Entameba histolytica cysts in untreated water can cause amoebic dysentery

Ciliophora

Commonly called ciliates Move via cilia Heterotrophic Largest group of protozoans Mostly in freshwater, some marine Examples

› Paramecium› Stentor› Vorticella

Cilia may be modified into teeth, paddles, or feet

Form protective cysts to survive unfavorable conditions

Have 2 types of nuclei› Micronuclei› Macronuclei – controls asexual

reproduction by mitosis Can reproduce sexually by conjugation Gases diffuse across cell membrane

Stentor

Trumpet shaped Cilia around top Attaches to feed, then detaches to

swim around

Vorticella

Cup shaped protozoan Cilia at the top Has a coiled stalk to raise and lower

organism Can attach to surfaces Can disappear…

Paramecium

Slipper shaped Clear, elastic covering of cell

membrane called pellicle (made of protein)› Used for protection

Uses cilia to swim and obtain food (algae & bacteria)

…. Cilia sweeps food

into oral grooves where mouth is located at the bottom

Food enters short tube called gullet into food vacuoles where it is digested

Waste leaves through anal pore

Have trichocysts› Toxic darts to help capture prey

Respond to light and learn by trial & error Reproduce asexually by mitosis &

sexually by conjugation

Sporozoa

Commonly called sporozoans No movement in adults Heterotrophic Examples

› Plasmodium› Toxoplasma

Form spores Most are parasitic Immature

sporozoans are called sporozoites and live in body fluids of hosts

Plasmodium sporozites enter the bloodstream, travel to the liver, divide and form spores called merozoites

Merozoites attack rbc’s and later form eggs and sperm that fertilize

New sporozites migrate to the salivary glands of mosquitoes where they can be passed on to another person

Fungus-like Protist Heterotrophic Multi-cellular Unique life cycles with 2 phases Found in moist watery habitats Act as decomposers

› Breaking down dead organic matter Includes:

› Slime molds› Water molds› Chytrids

Slime Molds

Shiny, wet appearance Usually bright colored Life cycle has 2 phases

› Mobile feeding stage› Nonmotile reproductive

stage Make a reproductive

structure or fruiting body that produces spores

Feeding stage of slime mold

plasmodium

Fungal – like in nutrition (absorptive heterotrophs that break down dead organic matter)

Saprophytes or parasites

Saprophytic slime mold pseudoplasmodium

A. Lycogala epidendrumB. Comatricha typhoidesC. Badhamia utriculariaD. Dictydium

Plant-like Protist A.K.A. algae

Eukaryotes Unicellular and multi-cellular Autotrophic - chloroplasts Produce oxygen that is returned to the

atmosphere Huge ranges in sizes No roots, stems, or leaves Some have flagella at some point in life

cycle and contain pyrenoids

Structure of algae

The body of algae is called thallus. Usually haploid. Varies b/w species.› Unicellular› Colonial› Filamentous› Multicellular

…unicellular algae… Single-celled Mostly aquatic Makes up bases of food chain Produces the major portion of oxygen

Chlamydomonas

…colonial algae… Groups of cells working together Allows more efficient movement,

feeding, and reproduction Volvox

…filimentous algae…

Have slender rod-shaped thallus composed of rows of cells joined end to end

May be secured to the ocean floor by holdfasts as it grows toward sunlight

…multicellular algae…

Often have a large, complex leaf-like thallus and may have stem-like section and air bladders

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Algae absorbs its flagellum Haploid algal cell then divides by mitosis

2-3 times 4-8 haploid flagellated cells called

zoospores develop in parent cell Zoospores break out of the parent cell

and eventually grow to full size

Haploid cells divide by mitosis to produce gametes

2 of these come into contact w/ each other, shed their cell walls, and fuse to form a diploid zygote

Resting stage of zygote is zygospore – can withstand bad environmental conditions

The thick wall opens and living zoospore emerges

Unicellular Reproduction, Chlamaydomonas

Reproduction in multicellular algae

Oedogonium reproduces sexually by producing male & female gametes. Sperm, released into surrounding water, swim 2 the egg.

Conjugation 2 filaments align side

by side, adjacent cell walls dissolve, and a conjugation tube forms between them

Gamete moves through the tube & fuses to another

Zygote forms a thick walled spore called sporangium that breaks away and forms a new filament

Reproduction via alternation of generations…

2 multicellular phases:› Gametophyte - haploid,

gamete producing phase› Sporophyte – diploid, spore

producing phase Equal in appearance &

duration

Classification of Algae

7 phyla:› Color› Type of chlorophyll (in addition to

chlorophyll a)› Form of food storage substance› Cell wall composition

Chlorophyta – green algae

Unicellular, colonial, filamentous, or multicellular

Chlorophyll a & b Carotenoids Starch is source of

food storage Cell wall composed

of cellulose May live

symbiotically as lichens

Thought to give rise to terrestreal plants

Phaeophyta – brown algae

Multicellular Chlorophyll a

& c, carotenoids, fucoxanthin (brwon pig.)

Uses laminarin as food storage

Cell wall made of cellulose and algin

Kelp & seaweed

Brown algae found in cold waters

Rhodophyta – red algae

Multicellular Chorophyll a,

phycobilins, & carotenoid

Uses starch as food storage

Cell wall contains cellulose, CaCO3, & agar3

Bacillariophyta - Diatoms Unicellular, some r colonial Chlorophyll a &c,

carotenoids, and xanthophyll

Stores food as starch Contains pectin and SiO2

in the cell walls No cilia or flagella When they die, form

diatomaceous earth that is abrasive and used in detergents, toothpaste, and fertilizers

Dinoflagellata – (Dinoglaellates) Unicellular

Chlorophyll a & c and carotenoids

Uses starch as food storage

Has cellulose in cell wall; makes armor like plates & spines

…Dinoflagellates…

Major producer in ocean Usually have 2 flagella

that spins and moves Produce a toxic

substance and causes red tides

Some produce light via bioluminescence

Chrysophyta – golden algae

Unicellular and some colonial

Chlorophyll a & c, carotenoids, and xanthophyll

Uses laminarin to store food

Contains cellulose in cell wall

Can produce highly resistant cysts to survive beneath frozen lakes

Euglenophyta - euglenoids

Unicellular chlorophyll a & b, carotenoids,

and xanthophyll Uses paramylon

(polysaccharide) as food storages

Has no cell wall, but has a pellicle (flexible protein covering)

Freshwater, moist soil, and some GI tracts

Can be heterotrophic in the absence of light

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